by Larry Niven
* * *
Pilgrim One gave them a breathless run across ochre deserts at high speed. A glimpse of something in flight. More desert.
Pilgrim Two: ochre sand, a claustrophobic run through a sandstorm, then more sand and a line of gray-green. Miya’s breath caught. Ra Chen slowed the view to real time.
Alien greenery, so flat that the low-built Pilgrim could look straight across six klicks’ width of dry-looking vines. A row of small triangular heads peeped out of the web of dusty-green fiber to watch the Pilgrim pass. Infrared showed the heads as red dots: warm-blooded.
The plants showed spectra of chlorophyll and water. If there was free-running water, it must run beneath the plants.
“Mars has … had gigatons of water. Where did it all go?” Miya wondered.
Gorky said, “The Orbiter only found a few small seas. Most of the water must be already in the canals.”
One of the animals pulled free and charged the Pilgrim. Body like a ten-legged weasel, face like nightmare, all teeth and hunger.
“I’ll call,” Willy Gorky said. To leave the viewing room must have been like pulling his own teeth, and he surely heard Ra Chen’s chuckle, but he hurried. Nobody else could be allowed to break this news to the Secretary-General!
And the rest settled back to watch the show.
Pilgrim Two ran fast-forward alongside the canal with ten-legged weasels biting at it, then turned suddenly. Ra Chen slowed again to examine a slender arc of freestanding bridge, ornately carved. Pilgrim Two crossed, watched impassively by an inhumanly tall and slender woman in a golden mask, and rolled on into red desert.
Ra Chen began flashing from one Pilgrim to another. He was trying to pull too much data too fast:
Pilgrim Three rolled into thick ice at the south pole, and froze up.
Pilgrim Four was approaching dwellings when creatures on riding beasts attacked and disabled it with swords. Ra Chen froze the frame on dwellings like clusters of crystal pillars, elegant and fragile and ancient. Then on the attackers. Weapons in three hands out of four; bipedal; green skin; faces like overgrown insects.
“Two species! Unbelievable. We’ll have to…” Ra Chen trailed off. No telling what might be needed at this point, or what he would have for resources.
Pilgrim Seven was crossing a web of valleys. Running the record at high speed made everyone seasick; Ra Chen had to stop. Up, down, up, down. “Valles Marineris,” Miya said. “It was bad enough when it wasn’t choked with greenery.”
Gorky was back. He said, “Seven’s not getting anywhere. Leave it.”
Pilgrim Eleven rolled out of a sandstorm and found a smooth stone wall. It rolled placidly along the wall, seeing nothing.
Pilgrim Eight rolled among low red hills toward cloudless blue sky. A dark vertical line appeared intermittently when the Pilgrim was looking up. Some flaw in the camera? Ra Chen went into fast-forward and they bore the motion sickness as Pilgrim Eight rolled out of the hills and down toward intersecting canals. A town looked to have grown up around the base of what was no longer a vertical thread, but a slender pillar in pale brown.
“It’s a tree,” Svetz said.
The Heads turned full around. Ra Chen barked, “Svetz, are you sure?”
“I’ve seen trees.”
And so had any of the few allowed into Waldemar Eight’s Garden, but Svetz had seen them by hundreds and thousands, dozens of kinds of trees—“Most of them branch out like a family lineage diagram, you know? But a few just keep going up and up. Ash does that. Redwoods … you can’t hold it in your head. It’s like they’re holding up the sky. Can you make the Pilgrim look straight up? How tall is that thing?”
Miya’s grip was a vise on Svetz’s wrist. “Hanny! Not just a tree. Willy!”
Noises outside: limousines. Then chaos rolled into the theater and everything came to a stop. Gorky’s guards were followed by twenty conspicuously armed giants in United Nations Security uniforms. They searched the viewing room and strip-searched its occupants and threw half of them out before they let the Secretary-General enter.
Svetz saw a crown or headdress rising above the guards. It was all Svetz could see of the Secretary-General. The middle of the front row was a kind of throne, and the space in front of it had been cleared.
Waldemar the Eleventh sat down. His voice held absolute confidence and a bit of a stutter. “Willy, s-show me what you’ve got.”
9
Its roots, trunk and branches bind together Heaven, Earth and the Netherworld.
—“The Ash Tree,” from Mattioli’s Commentaires, Lyons, 1579
Pilgrim Eleven rolled along a wall painted with nightmare figures faded to ominous shadows. The wall curved away; glass towers poked above its rim, barely glimpsed as the Pilgrim rolled into wilderness.
Pilgrim Four’s last moments showed alien shapes on alien riding beasts, and hacking silver blades. United Nations guards shrank closer around Waldemar the Eleventh.
A slender vertical thread became an impossibly tall pillar, the center of a township of tall, spindly towers. Pilgrim Eight rolled past, many klicks wide of the town and the great pillar. Ra Chen froze the frame.
Waldemar the Eleventh asked, “How tall is that?”
Gorky relayed the order down. “Ra Chen, we need a better view of that.”
Ra Chen said, “Formulate your instructions for the Pilgrims and we’ll send ’em. Do you know what to tell the Collector probe? Do you know what samples you want sent back to Earth?”
Gorky said, “We need a view up. I’d think we want seeds, if it makes seeds, and a lot more information.” His eyes flicked toward the Secretary-General. He would speak on any subject the SecGen raised first.
Pilgrim Eight ran straight to a canal, paused, then rolled in. Finding no easy way out, it followed the canal, sending out its light-enhanced viewpoint. Eyeless things fled from motion or the taste of metal. Queer near-human skeletons in skimpy armor, and far-from-human exoskeletons enhanced with miniature frescoes and artificial ribbing, lay intermingled along more than a klick of canal bottom.
Pilgrim Nine reached the northern ice and froze up. Gorky felt Ra Chen’s eyes on him and said, “We weren’t expecting significant ice.”
Pilgrim Ten rolled northeast until a canal blocked its path. It followed the canal to a crossing canal, rotated, and found a freestanding arched bridge, fantastically long and slender. It rolled onto the bridge and into a city. Family groups stopped to watch it pass. Men, women and children, they seemed of an unknown human race, with scarlet skins and narrow lips and noses. In martian cold they dressed in little more than weapon belts and jewels. Armed nudists, looking very mammalian.
Miya whispered into a recorder. “Look for antifreeze in their blood.”
Two women pushed a carriage like the cart for a dole beer keg. “Freeze that,” Willy Gorky snapped. “Zoom.”
It was rounded, the reddish-brown of martian sand, about a liter in size: an egg nested in fluffy cloth.
The Secretary-General spoke, and all other sound chopped off. “Well, Willy, you d-did it. Aliens. Alien civilization. What next? How big is your Collector d-device? Can you bring me an ambassador?”
“Ultimately I can bring a whole family, Mr. Secretary”—Gorky’s eyes flicked to Ra Chen and saw his nod—“and house them in the Vivarium, but it might take years.”
“Egg of a Martian, then. Something soon,” Waldemar Eleven said, and Svetz thought: In time for the coronation.
Gorky said, “I don’t know how to keep an egg alive. Easier with an adult Martian, I think. Mr. Secretary, I’d rather get some seeds from that tree.”
They had seen only one object that might be called a tree. The SecGen didn’t ask which. “Why?”
It was a strange conversation, Svetz thought. One did not speak to the Secretary-General without invitation. Gorky daren’t even volunteer information, and that meant that the SecGen himself had to ask all the right questions. A rare skill.
“I want a look up,”
Willy said. “Mr. Secretary, I think that tree is an orbital tower, a Beanstalk. If it is, we’ll take the whole solar system for no more than the budget we were getting from Waldemar the Tenth. Square klicks of orbital powersats. Asteroid mines. We’ll set colonies on Mars and Europa and floating in the atmospheres of Jupiter and Saturn and Venus. We’d need to plant one of these on Earth. We’d need seeds—”
“Can you even f-find it again? It looked thin as a d-dream,” the SecGen said. “Willy, I’ve been trying to find the mmm, outlines of Syrtis Major and I can’t. The canals and vegetation change everything.”
“Measure from Mons Olympus, Mr. Secretary. The tree’s at twenty-seven degrees two minutes longitude, zero latitude,” said Willy Gorky.
“Can your Collector device climb a tree?”
“No. Maybe we’ll find seeds near the base.”
“What’s this going to cost me?” asked the SecGen.
“At least two more probes. Use of the time machine three times, maybe more. Maybe a manned expedition. Ra Chen?”
They talked money.
Svetz tuned it out. “Miya, we’ve found cities on Mars, and all they’re talking about is that tree!”
“It might be, it just might be a Beanstalk. How else could it stand up at all?”
“Don’t understand the question.”
She started to answer, but the SecGen was departing. In their mania for order, his guards were turning all into chaos.
10
Jesse’s rod (stem). The animating and energizing force or light of Jesse; a genealogical tree; a phallus. Sometimes represented by a vine, thus equating with the beanstalk, Jacob’s ladder, or Lugh’s chain.
—Dictionary of Mythology, Folklore and Symbols, by Gertrude Jobes
A man in Space Bureau uniform lectured the Institute people. “Geosynchronous orbit is 35,700 klicks above the Earth. Whatever you set in orbit at that height will circle the Earth in exactly a day. It’s a privileged position, because the Earth circles itself in exactly a day…”
Svetz got lost. So he tracked down Miya afterward and asked her.
“Hanny, it’s a wonderful notion. You know what synchronous orbit is? It’s where we put the weather satellites.”
“No.”
“Um. Suppose you’re orbiting just outside the atmosphere. You go ’round the Earth in an hour and a half, right? Higher, it’s a bigger circle and you’d move slower. Takes longer. As high as the Moon, it takes almost a month to go around. Right?”
“Right.”
“Somewhere in between is where it takes just twenty-four hours. For the Earth it’s 35,700 km up. That’s synchronous orbit. The Earth is spinning as fast as you’re moving, so you stay above the same point.”
“Okay.”
“I take a coil of good strong rope. I set it moving above the equator with its center of mass at synchronous orbit. Now the coil stays just over a point on the equator, right?”
“Right.”
“Now I reel the rope out until one end is on the ground and the other end is way out there for balance.”
“That’s your orbital tower?”
“Right. Now I run an elevator up and down the rope. I use it to lift cargo for the price of electric current plus any profit I can get away with. If I go past the synchronous point and then let something slide up along the rope, it’ll fly off the far end with enough velocity to reach the asteroids.”
“It’s a tree, but it’s hanging from the sky?”
“Yes, exactly!”
Svetz rubbed his eyes. He said, “That would cost … I can’t imagine what it would cost. And you think you’ve found such a thing?”
“Hanny, what made you say it was a tree?”
“It … reminded me of a redwood. It went up and never seemed to stop.”
“Like Yggdrasil! Like the world-tree from Norse legend!”
“But no tree could be strong enough! Steel wouldn’t be strong enough—”
“No, Hanny, hold on. An orbital tower has to be strong, right? If you build it around Mars, you get high rotation and a lower mass, much lower, so it doesn’t have to be as long or as strong. Picture it a hundred thousand klicks long, and the only thing strong enough is still carbon crystal fibers or fullerine tubules, and those are carbon too.
“I think you were right. We can’t make such a thing, we don’t have anything to make it out of, so why can’t it be a tree? Life is carbon based. Trees are good at manipulating carbon. And if we had seeds, we would go to the planets for nothing more than electricity!”
Svetz, Miya, Zeera, and most of the techs slept on air cots in the Center while a composite team of Sky Domains and History Bureau wrote instructions for the probes on archaic Mars.
In the morning they were back in the small extension cage.
* * *
Gravity shifted. They floated toward each other, bumped skewed, and pulled themselves around. The clothing they stripped off kept floating back like intrusive ghosts. They made a game of batting garments away.
“Hanny! How many times do we have to do this before I’m a virgin again?”
Svetz laughed. “I’ve never gotten less hungry on any trip.”
And later he asked, “Are we going for a record this time?”
“Mmm. Duration? Number? Intensity?”
“Not unless I get some rest.”
“Someday I’m going to get you in a bed.”
Svetz didn’t answer. Miya asked, “What’s the matter?”
“I had this notion once. Miya, we’re going back to before time travel was even a concept. Once it was fantasy, fairy-tale stuff. In the late Industrial Age, Thorne and Tipler and some other top mathematicians showed that time travel was theoretically possible and did some designs. The Institute for Temporal Research came out of those. What if everything we collect from before plus-thirty Atomic Era is fantasy?”
“Hard to picture Whale as a fantasy! He’s too big,” Miya said. “Too scarred, too detailed. When you pulled him in, wasn’t there a one-legged sailor still tangled in the lines and harpoons along his flank? That’s gritty realism, that is!”
Svetz smiled. “Gila Monster would have charred me if I’d thought he was a fantasy. Horse tried to spear me like a wine cork.”
“So.”
“You’re an adolescent’s daydream,” he told Miya. She purred into his throat, and he said, “And here we are, but we’ve never made love after plus-thirty AE. Maybe you’re my fantasy.”
“Am I? Great. Are you ticklish? Is this real? Is it?”
* * *
In the old days they had used the time machine to set a two-milligram test mass alongside itself. The experiment ate energy equivalent to the test mass times lightspeed squared. Bringing an X-cage to a spacetime it had already occupied would cause a surge in energy consumption. That was how it could return to its point of departure.
The small X-cage emerged just too late to watch itself vanish.
This mission would be cheap. They were only messengers, the messages already written.
To the Orbiter module: a burn to put it in a higher orbit.
“Excuse me?”
“It’s in low Mars orbit now, Hanny. We don’t want it hitting the tree. It’s only luck that hasn’t happened yet!” Miya kept working. “Of course the current Collector module won’t be able to fly that high. We’ll instruct the Orbiter to dive down and get it, and I hope somebody’s writing that program.”
The Tanker was already fully fueled and awaiting the arrival of a loaded Collector. No message needed.
To the Pilgrims: converge on the skyhook tree at twenty-seven degrees two minutes longitude, zero latitude. Pan up and down. Focus every instrument on the tree.
To the Collector: follow the Pilgrims. Where they converge, find a high point and watch them. Defend against molesters.
“We’ve already lost four Pilgrims. We can afford that, but we can’t lose the Collector. All right, Hanny. Jump us by a year and we’ll collect what they get.�
�
Svetz dipped them into time, watched, tripped the interrupt. They’d jumped over two years. Miya sent the instructions. “Mars is close. Only about eighteen minutes this time,” she said.
“Miya, doesn’t Mars have two moons? Why haven’t they chewed up the tree?”
Miya chewed her underlip. She turned to the control board.
“Miya?”
“I’m looking! The top of the tree doesn’t taper off; it ends in a knob. Deimos is further out than that, but Phobos … Phobos is below synchronous orbit, it has to be, it goes around more than twice a day! Orbit’s a little skewed, but it crosses the equator. It can’t just keep missing!”
“Doesn’t sound like your space elevator has been in place very long at all.”
Miya said, “Yesss. Hanny, you have a knack for … ah, penetrating fantasies. It would have had to grow very fast, wouldn’t it?”
“Or arrive already grown.”
* * *
Message bursts from archaic Mars were streaming in. Miya checked to see that they were recording, and then Svetz set them moving forward through time to the present.
11
Lugh’s chain. The Milky Way, chain by which Lugh raised men to heaven … Equated with Bifrost, Jacob’s ladder, the stem of Jesse, Watling Street.
—Celtic mythology, Dictionary of Mythology, Folklore and Symbols, by Gertrude Jobes
1108 AE. It’s a tree. In proportion it’s as slender as an ash tree—no, more! But near the ground it bifurcates and spreads. Scores of near-vertical roots sink deep. The sixty-fingered hand covers the green breadth of a canal and a square klick of ochre desert on each side. Wreckage of a bridge rides high in the tangle of roots. Other, newer bridges in slender martian style stretch around and between other roots.
Wait now, that wrecked bridge was lifted, as if the tree’s roots rose from the ground. How could a tree grow from the ground to orbit? Nothing could be that strong!
Paired silver lines rise along a vertical root and far up along the trunk. Look up: the tree rises out of sight. Silver lines continue as far as the eye can see.